Electrical system for an aerosol generator

Abstract

An aerosol generating device is disclosed that includes an electrical system (20). The electrical system (20) includes a battery (22) and a control circuit (24). The control circuit (24) is configured to monitor the status of the battery (22) during a discharge operation and set a flag if a fault in the battery (22) is detected, the flag indicating that the battery (22) is not in an operational state. The control circuit (24) is also configured to check the flag when the electrical system (20) is connected to an external power source and enable charging of the battery (22) based on the flag. The battery (22) and the control circuit (24) are connectable to an external power source via a first electrical path (36) and a second electrical path (38), respectively, so that power can be independently supplied to the battery (22) and the control circuit (24). The electrical system (20) is configured to provide power to the control circuit (24) from the external power source via the second electrical path (38) when the electrical system (20) is connected to the external power source, allowing the flag to be checked without charging the battery (22).

Description

[Technical field]

[0001] The present invention relates to electrical systems, particularly for use in aerosol generating devices. [Background technology]

[0002] Aerosol generating systems, such as electronic cigarettes, often include an electrical system with a battery to power a heating element. In such systems, a known problem is that the battery may enter a deep discharge state. For example, when a lithium-ion battery cell enters a deep discharge state, internal degradation, known as copper electrode dissolution, may occur within the battery cell, and a short circuit may be created between the cell electrodes. When such a battery is recharged, the cell is prone to overheating and thermal runaway, which may potentially pose a safety hazard.

[0003] There are many other battery conditions that pose potential safety risks, and operation of a battery that exhibits such conditions should generally be avoided. Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present invention to improve the safety of electrical systems, including batteries, within aerosol generating devices. [Means for solving the problem]

[0005] According to an aspect of the present invention, an aerosol generating device is provided that includes an electrical system, the electrical system including a battery and a control circuit, the control circuit configured to monitor the status of the battery during a battery discharge operation and set a flag if a battery fault is detected, the flag indicating that the battery is not in an operational state, the control circuit configured to check the flag when the electrical system is connected to an external power source, the control circuit configured to enable charging of the battery based on the flag, the battery and the control circuit are connectable to an external power source via a first electrical path and a second electrical path, respectively, such that power can be supplied independently to the battery and the control circuit, and the electrical system configured to supply power from the external power source to the control circuit via the second electrical path when the electrical system is connected to the external power source, such that the flag can be checked without charging the battery.

[0006] In this manner, damaged or otherwise degraded batteries may be prevented from being charged, thereby improving the safety of the electrical system.

[0007] Existing strategies for dealing with battery faults involve monitoring the charging curve of the battery to detect deep discharge or other dangerous battery conditions. However, such strategies only detect faults after charging of the cells has begun. Thus, power may already be being supplied to a battery with an internal short circuit or other fault. In the present invention, the control circuit monitors the battery during a discharge operation, e.g., when powering the heating element during a vaping operation of the aerosol generating device, and sets a flag in the control circuit if a fault is detected. Then, when the electrical system is connected to an external power source with the intention of charging the aerosol generating device, the control circuit checks the flag and enables charging of the battery only if the flag is present. As a result, charging of the battery is prevented from beginning if the battery is faulty, thereby ensuring that a battery in a dangerous situation does not receive power.

[0008] Moreover, the electrical system is configured such that the control circuitry can be powered and the flag checked without also powering a potentially defective battery. By comparison, in known electrical systems, particularly in aerosol generating devices, powering the control circuitry also initiates the charging process, meaning that the flag cannot be checked without also powering a potentially dangerous battery.

[0009] Detecting a battery fault may include measuring the voltage of the battery over time. When the voltage falls below a threshold voltage, it may be determined that a fault has occurred. In one example, for a lithium-ion battery, 3.0V may be a typical voltage at which a battery is considered discharged, 2.8V may be a typical threshold below which a battery is considered faulty, and 2.5V may be a typical voltage at which a battery has irrecoverable internal cell damage. However, one skilled in the art will understand that the threshold voltages will vary depending on the type of battery and the particular cell chemistry.

[0010] Alternatively or additionally, detecting a fault in the battery may include monitoring the temperature of the battery. If the temperature of the battery exceeds a threshold temperature, the battery may be determined to have a fault. Those skilled in the art will understand that the threshold temperature will vary depending on the type of battery and cell chemistry.

[0011] Preferably, the electrical system further includes a battery charger circuit, the control circuit configured to send a signal to the battery charger circuit based on the flag, the signal indicating that charging is enabled, and the battery charger circuit configured to charge the battery upon receiving a signal from the control circuit indicating that charging is enabled. In this manner, use of the battery charger circuit ensures that power is efficiently and reliably delivered to the battery, while the signal reception requirement ensures that power is not delivered to a damaged or degraded battery.

[0012] Preferably, charging the battery includes supplying power to the battery along a first electrical path.

[0013] Preferably, the control circuitry is configured to modify the flag upon detecting that the battery has been replaced, in this manner, new batteries that are not in a potentially unsafe operating condition are not prevented from being charged.

[0014] Preferably, the electrical system further includes a voltage regulator for powering the control circuitry. The voltage regulator has the ability to generate and maintain a constant current or voltage output.

[0015] In one embodiment, the electrical system may be connectable to an external power source via a USB connection, in particular the voltage regulator and battery charger circuitry may be connectable to an external power source via a USB connection.

[0016] Preferably, the electrical system is configured to power the control circuitry from a battery when the electrical system is not connected to an external power source.

[0017] Preferably, the electrical system further comprises a heating element, and the control circuit is configured to switch off the power supply from the battery to the heating element when a fault is detected in the battery, thus avoiding continued operation of a damaged or otherwise degraded battery.

[0018] Preferably, the control circuit is configured to switch off the power supply from the battery to the heating element when the electrical system is connected to an external power source.

[0019] Preferably, the electrical system further includes a fuse, and the control circuit is configured to activate the fuse when a fault detected in the battery is deemed irreversible, the activation of the fuse irreversibly disabling charging of the battery.

[0020] Preferably, the control circuitry is further configured to activate the fuse when a threshold time has elapsed since the flag was set and a fault in the battery is detected as still present.

[0021] According to another aspect of the present invention, a method of operating an aerosol generating device including an electrical system is provided, the method including using a control circuit to monitor a status of a battery in the electrical system during a battery discharge operation, and in response to detecting a battery fault, setting a flag indicating that the battery is not in an operational state, wherein the battery and control circuit are connectable to an external power source by a first electrical path and a second electrical path, respectively, so that power can be supplied independently to the control circuit and the battery, and in response to detecting that the electrical system is connected to the external power source, supplying power from the external power source via the second electrical path to check the flag without charging the battery, and enabling charging of the battery based on the flag.

[0022] Preferably, the method further includes sending a signal from the control circuit to the battery charger circuit indicating that charging is enabled, and charging the battery in response to receiving the signal indicating that charging is enabled.

[0023] Preferably, the method further comprises clearing the flag upon detecting that the battery has been replaced.

[0024] Preferably, the method further includes powering the control circuit from the battery when the electrical system is not connected to an external power source.

[0025] Preferably, the method further comprises providing a heating element in the electrical system and switching off the power supply to the heating element when a fault is detected in the battery and / or switching off the power supply from the battery to the heating element when the electrical system is connected to an external power source.

[0026] Preferably, the method further includes using the control circuit to activate a fuse in the electrical system when a fault detected in the battery is deemed irreversible, the activation of the fuse irreversibly disabling charging of the battery.

[0027] Preferably, the method further includes operating, using the control circuitry, a fuse in response to detecting that a threshold time has elapsed since the flag was set and that a fault in the battery is still present.

[0028] According to another aspect of the present invention, a non-transitory computer-readable storage medium is provided that, when executed on a computer or processor in an aerosol generating device including an electrical system, causes the computer or processor to perform steps including: using a control circuit to monitor a status of a battery in the electrical system during a battery discharge operation; and in response to detecting a fault in the battery, setting a flag indicating that the battery is not in an operational state, wherein the battery and control circuit are connectable to an external power source by a first electrical path and a second electrical path, respectively, so that power may be supplied independently to the control circuit and the battery; and in response to detecting that the electrical system is connected to the external power source, supplying power from the external power source via the second electrical path to check the flag without charging the battery; and enabling charging of the battery based on the flag.

[0029] Embodiments of the invention will now be described, by way of example only, with reference to the drawings in which: [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a block diagram of a prior art electrical system for an aerosol generating device. [Diagram 2] FIG. 2 is a block diagram of an electrical system for an aerosol generating device in one embodiment of the present invention. [Figure 3A]3 is a block diagram of the electrical system depicted in FIG. 2 illustrating a first electrical path for supplying power from an external power source to a battery and a second electrical path for supplying power from the external power source to a control circuit. [Figure 3B] 3 is a block diagram of the electrical system depicted in FIG. 2 illustrating a third electrical path for providing power from the battery to the control circuitry during a battery discharge operation. [Figure 4] 2 is a flow chart illustrating method steps for operation of an electrical system for an aerosol generating device in one embodiment of the present invention. [Diagram 5] 5 is a flow chart illustrating further method steps for operation of the electrical system. [Figure 6] FIG. 2 is a block diagram of an electrical system for an aerosol generating device in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] 1 shows a prior art electrical system 2 for an aerosol generating device. The electrical system 2 includes a battery 4, a control circuit 6, a battery charging circuit 8, a power connector 10, a heating element 12, and a switch 14.

[0032] In use, when the electrical system 2 is connected to an external power source via the power connector 10, the battery charging circuit 8 delivers power to activate the control circuit 6. However, because the battery 4 and the control circuit 6 are connected in parallel and are powered directly by the battery charging circuit 8, the battery 4 also receives power and begins to charge. Therefore, utilizing any function of the control circuit 6 also causes the battery 4 to receive power.

[0033] 2 shows an electrical system 20 for an aerosol generating device in one embodiment of the present invention. The electrical system includes a battery 22, a control circuit 24, a battery charging circuit 26, a USB connector 28, a voltage regulator 30, a heating element 32 and a switch 34.

[0034] The USB connector 28 is connectable to an external power source. Those skilled in the art will appreciate that the USB connector 28 may be replaced with another suitable form of power connector, such as any alternating current (AC) power plug for connecting to a primary AC power supply in a building, or a direct current (DC) power plug for supplying DC power.

[0035] As illustrated in FIG. 3A , electricity may be provided from the USB connector 28 to the battery 22 along a first electrical path 36. The first electrical path 36 runs from the USB connector 28 to the battery 22 via the battery charging circuit 26. Electricity may also be provided from the USB connector 28 to the control circuit 24 along a second electrical path 38. The second electrical path runs from the USB connector 28 to the control circuit 24 via the voltage regulator 30. The first electrical path 36 and the second electrical path 38 are configured as separate and distinguishable electrical paths. Thus, when the USB connector 28 is connected to an external power source, electricity may be provided along the second electrical path 38 to power the control circuit 24 without also powering the battery 22. As used herein, the term “electrical path” refers to a component suitable for transmitting power by the conduction of electrons, such as a wire, cable, or power line.

[0036] 3B, a third electrical path 39 connects the battery 22 to the control circuit 24 through the voltage regulator 30. The battery 22 may be a lithium ion battery, a nickel cadmium battery, a nickel metal hydride battery, a lead acid battery, or any other type of rechargeable battery.

[0037] In use, the voltage regulator 30 either receives power from an external power source (via the USB connector 28) or receives power from the battery 22. The voltage regulator 30 can then provide electricity to the control circuit 24 to activate and power the control circuit 24. The voltage regulator 30 is configured to power the control circuit 24 with power from the USB connector 28 when the electrical system 20 is connected to the external power source (i.e., power is provided along the second electrical path 38), and is otherwise configured to power the control circuit 24 with power from the battery 22 (i.e., power is provided along the third electrical path 39).

[0038] Voltage regulator 30 has the ability to generate and maintain a constant current or voltage output. It is understood that in alternative embodiments, voltage regulator 30 may instead include switches or other mechanisms that allow the supply of current to be controlled and / or adjusted and directed along different electrical paths.

[0039] In this embodiment, control circuitry 24 is a microcontroller unit (MCU) and is used to control the operation of electrical system 20. The MCU includes one or more CPUs (processor cores) along with memory and programmable input / output peripherals. In other embodiments, control circuitry 24 may include separate microprocessors, memory, and input / output devices.

[0040] The control circuit 24 is configured to monitor the status of the battery 22 during a discharge operation of the battery 22 and control one or more aspects of the electrical system based on the status of the battery 22. The term "discharge operation" of the battery refers to when the battery 22 is used as a power source to power electrical loads or electrical components in the electrical system 20. Monitoring the status of the battery 22 may include monitoring one or more properties or characteristics of the battery 22, such as temperature, voltage, or current, to detect faults or anomalies in the battery 22.

[0041] For example, a fault may result from the battery 22 entering a deep discharge state that leads to internal degradation of the battery, e.g., a short circuit. This may be detected by measuring the battery 22 voltage over time and determining when the voltage falls below a threshold voltage. The threshold voltage will vary depending on the type of battery and the particular cell chemistry. However, as an example, for a lithium ion battery, 3.0V may be a typical voltage below which the battery is considered discharged, 2.8V may be a typical threshold below which the battery is considered faulty, and 2.5V may be a typical voltage below which the battery has irreparable internal cell damage. This internal damage is often referred to as copper (foil) melting.

[0042] A fault condition may also be determined by monitoring the temperature of the battery 22. A temperature sensor 27 may be used to measure the temperature of the battery. If the battery is operating abnormally, the temperature will likely be high. Thus, if the temperature is detected to exceed a threshold temperature, the battery 22 may be determined to have a fault. Again, the threshold temperature will vary depending on the battery type and cell chemistry.

[0043] A further example of detecting a fault may include detecting battery capacity loss. Capacity loss (or capacity fading) is a phenomenon observed during use of rechargeable batteries, where the amount of charge the battery can deliver at its rated voltage decreases with use. For example, when the battery capacity fade exceeds approximately 60%-70%, the battery may be considered too old / damaged and therefore faulty.

[0044] In this case, the electrical system 20 is located within an aerosol generating device, and the discharging operation refers to the aerosol generating operation (or vaping operation) in which the battery 22 is providing power to the heating element 32. However, those skilled in the art will appreciate that the electrical system 20 may be used in alternative devices, and the heating element 32 may be replaced with other electrical components.

[0045] The control circuit 24 is configured to set a flag in the data store 25 of the control circuit 23 when a fault is detected in the operating condition of the battery 22. The data store 25 may include volatile or non-volatile memory, or may include long term storage. The flag provides an indication that a fault has been detected and the battery 22 is not in an operating condition.

[0046] In this embodiment, the flags are a form of status registers that are set in an EEPROM (electrically erasable programmable read-only memory) of the MCU 24 to record the status of calculations performed by the MCU 24. Typically, the flags are defined as one bit of data in the EEPROM, but may have more bits to indicate the particular type of fault that was detected.

[0047] The control circuit 24 may also be configured to open the switch 34, thereby cutting off the supply of electricity to the heating element 32, when a fault is detected in the battery 22, improving the safety of the aerosol generating device.

[0048] In one embodiment, electrical system 20 may further include a data line connecting control circuit 24 to electrical system 20 configured to provide voltage information to control circuit 24 .

[0049] To charge the battery 22, the electrical system 20 of the aerosol generating device can be connected to an external power source by a USB connector 28. A voltage regulator 30 receives power from the USB connector 28 and generates a CC (constant current) output that is used to power the control circuitry 24 by supplying electricity along a second electrical path 38. Because the battery 22 is connected to the USB connector 28 by a first electrical path 36 that is separate from the second electrical path 38, the control circuitry 24 can be powered without also charging the battery 22.

[0050] In response to being powered up by voltage regulator 30 when connected to an external power source, control circuit 22 is configured to check the flag. If the flag is present, control circuit 24 will not enable charging of battery 22. If the flag is cleared or not present, control circuit 24 will enable charging of battery 22.

[0051] Enabling charging of the battery 22 includes sending a signal to the battery charging circuit 26, which indicates that charging of the battery 22 is enabled. The battery charging circuit 26 is configured to charge the battery 22 only when it receives a charging enable signal from the control circuit 24. Charging of the battery 22 includes providing power to the battery 22 along a first electrical path 36. If no signal is received, the battery charging circuit 26 will not charge the battery 22. This configuration therefore ensures that the charging process cannot begin if there is a detected fault in the battery 22, thereby improving the safety of the aerosol generating device. This method of operation is facilitated by separate electrical paths 36, 38 for the battery 22 and the control circuit 24, respectively, which allows power to be provided to the control circuit 24 to check the flag without also charging the battery 22.

[0052] In this embodiment, the battery charging circuit 26 is a battery charger IC (integrated circuit).

[0053] Of other general purposes, the control circuit 24 may be configured to switch off the power supply from the battery 22 to the heating element 32 when the electrical system 20 is connected to an external power source through the USB connector 28. This may be accomplished by opening the switch 34. Moreover, the control circuit 24 may be configured to clear a flag if the control circuit 24 detects that the battery 22 has been replaced.

[0054] 4 and 5 illustrate a method of operation of the electrical system 20 of an aerosol generating device in one embodiment of the present invention.

[0055] 4, the method begins at step 40 when the aerosol generating device enters a vaping or aerosol generating mode of operation. During the vaping mode of operation, the battery 22 is used as a power source to power the heating element 32. The battery also provides electricity along a third electrical path 39 to power the control circuit 24.

[0056] In step 42, the control circuitry 24 monitors the condition of the battery 22. For example, the control circuitry 24 may monitor the battery 22 voltage over time to detect a deep discharge condition. If no fault is detected, the monitoring and vaping operations continue.

[0057] If a fault is detected, the switch 34 is opened and power is no longer provided from the battery 22 to the heating element 32, causing the aerosol generating device to terminate its vaping operation. Additionally, at step 46, the control circuit 24 sets a flag within the control circuit 24 indicating that the battery 22 is not operational.

[0058] Referring to FIG. 5, the method continues at step 48 when the aerosol generation device is connected to an external power source via the USB connector 28 with the intent of charging the battery 22 within the aerosol generation device.

[0059] Upon connection to an external power source, a CC output is generated by the voltage regulator 30 and provided to the control circuitry 24 along the second electrical path 38, step 50. Because the first electrical path 36 and the second electrical path 38 comprise separate conductive paths, the control circuitry 24 can be activated and powered without providing power to the battery 22.

[0060] At step 52, when control circuit 24 is activated, it checks the flag.

[0061] If the flag is cleared or not present, the method continues at step 54, where charging of the battery 22 is enabled. At step 56, the control circuit 24 sends a signal to the battery charging circuit 26 indicating that charging of the battery 22 is enabled. At step 58, when the battery charging circuit 26 receives the signal indicating that charging is enabled, the battery charging circuit 26 begins charging the battery 22 by providing power along the first electrical path 36.

[0062] Alternatively, if the flag is not cleared in step 52, the method proceeds to step 60 and charging of the battery is not enabled.

[0063] Figure 6 illustrates an electrical system 70 according to another embodiment of the present invention. The electrical system 70 includes features corresponding to those described with reference to Figures 2-5 and is configured to operate substantially in accordance with the methods of Figures 4 and 5 under certain conditions as described below. However, for ease of reference, some of the connections and features described above have been omitted from Figure 6. Nonetheless, one skilled in the art will understand that the omitted features, such as the heating element 32, may be used in conjunction with additional features of the present embodiment.

[0064] The electrical system 70 differs from the previous embodiment in that the electrical system 70 further includes a fuse 72 for disabling charging of the battery 22. The fuse 72 is in addition to the previously mentioned flag that may be set within the control circuit 24 to disable charging of the battery 22. That is, the electrical system 70 utilizes both hardware and software means to disable charging of the battery 22 when a fault is detected in the battery 22.

[0065] In particular, the flag mechanism described above provides a first level of protection to prevent charging of battery 22 when a fault is detected in battery 22, the fault being caused by a battery condition that is deemed (potentially) recoverable. Fuse 72 provides a second level of protection to prevent charging of battery 22 when a fault is detected in battery 22, the fault being caused by a battery condition that is deemed not recoverable.

[0066] Examples of damage to the battery 22 that may be considered irreparable include an internal short circuit. For example, as discussed above, a short circuit may result from the battery 22 entering a deep discharge state that leads to internal degradation of the battery 22. This may be detected by measuring the battery 22 voltage over time and determining when the voltage falls below a threshold voltage. Another sign of permanent, irreparable damage is the detection of a voltage drop during the charging process. Such a voltage drop suggests that the battery 22 has an internal short circuit.

[0067] On the other hand, an example of damage to the battery 22 that may be considered recoverable is capacity loss due to lithium plating. Lithium plating occurs under aggressive or suboptimal charging conditions. Such capacity loss can be recovered by preventing operation of the battery 22 for a period of time, for example several days, or by performing one or more charging cycles and monitoring the capacity evolution over time. However, in some circumstances, capacity loss due to lithium plating may not be recoverable, for example if the internal damage is too severe.

[0068] In this embodiment of the invention, if an irrecoverable fault condition of battery 22 is detected, such as detecting a voltage drop during charging or detecting that battery 22 has entered a deep discharge state, fuse 72 is activated by control circuit 24 to permanently disable charging of battery 22.

[0069] Otherwise, if a fault condition of the battery 22 that is not deemed irrecoverable is detected, for example, if a capacity loss of the battery 22 is detected and the capacity loss exceeds a threshold amount, the electrical system 70 operates in accordance with the previously described embodiment, i.e., a flag is set indicating that the battery 22 is not in an operational state, thereby preventing charging of the battery 22 while the flag is present.

[0070] However, if after a period of time has elapsed, it is detected that the fault condition is still present, the damage to the battery 22 may be deemed irreversible. In this case, the fuse 72 is activated by the control circuit 24 such that charging of the battery 22 is permanently disabled. For example, the fuse 72 may be activated if the capacity of the battery 22 remains below a threshold capacity, e.g., less than 50-40% of the nominal capacity, after a threshold time has elapsed. The control circuit 24 may include a timer configured to monitor the elapsed time, or alternatively or additionally, the control circuit 24 may estimate the elapsed time by monitoring the voltage evolution of the battery 22.

[0071] As will be appreciated by those skilled in the art, the fuse 72 is a physical component configured to blow when the current exceeds a predetermined level. For example, the fuse 72 may be comprised of a strip of wire configured to melt above a predetermined current level. In particular, the fuse 72 may include a copper track with a narrower center portion, as illustrated in FIG. 6.

[0072] In the particular implementation of the electrical circuit 70 illustrated in FIG. 6, the electrical system 70 includes an I / O line 74, a transistor 76 (e.g., an NPN transistor), an enable line 78, a resistor 80, and a positive supply voltage V cc An I / O line 74 extends from the control circuit 24 to the transistor 74. A first positive supply voltage V cc is connected to the I / O line 74 through a first resistor 80. A transistor 76 couples the fuse 72 and the second positive supply voltage V ccThe fuse 72 is connected to the charging circuit 26 via an enable line 78. A third positive supply voltage V CC is connected to the enable line 78 through a second resistor 80.

[0073] When a threshold time has elapsed since a fault deemed to be irrecoverable is detected in battery 22 or a flag is set, control circuit 24 is configured to send a signal along I / O line 74 to turn a transistor "on" so that maximum current flows through fuse 72. In this manner, fuse 72 is blown (i.e., activated), and enable line 78, connected to transistor 76 through a portion of fuse 72, provides a control signal to charging circuit 26 (e.g., set high) that permanently disables charging of battery 22.

[0074] Of course, those skilled in the art will appreciate that the particular configuration of electrical system 70 including fuse 72 illustrated in FIG. 6 is an example configuration, and that various modifications may be made to electrical system 70 that are within the scope of the claims.

Claims

1. 1. An aerosol generating device including an electrical system, the electrical system comprising: A battery; a physical component configured to interrupt a current flowing through the physical component when the current flowing through the physical component exceeds a predetermined level; a control circuit configured to monitor a condition of the battery and to detect a fault in the battery; the control circuitry is configured to determine a fault in the battery when the electrical system is connected to an external power source and to enable charging of the battery when there is no fault in the battery; the battery can receive power from the external power source via a first electrical path, and the control circuit can receive power from the external power source via a second electrical path; An aerosol generating device, wherein the electrical system supplies power from the external power source to the control circuit via the second electrical path when the electrical system is connected to the external power source, and the control circuit is configured to determine whether a fault in the battery has been detected without charging the battery.

2. a battery charger circuit, the control circuit configured to send a signal to the battery charger circuit to control operation of the battery charger circuit; The aerosol generating device of claim 1 , wherein the battery charger circuit is configured to control charging of the battery based on the signal.

3. 3. The aerosol generating device of claim 2, wherein charging the battery comprises supplying power to the battery along the first electrical path.

4. An aerosol generating device as described in any one of claims 1 to 3, wherein the electrical system is configured to supply power to the control circuit from the battery when the electrical system is not connected to the external power source.

5. An aerosol generating device as described in any one of claims 1 to 4, wherein the electrical system further includes a heating element, and the control circuit is configured to stop supplying power from the battery to the heating element if a fault is detected in the battery.

6. The aerosol generating device of claim 5 , wherein the control circuit is configured to stop supplying power from the battery to the heating element when the electrical system is connected to the external power source.

7. 1. A method of operating an aerosol generating device including an electrical system, comprising: a control circuit monitoring a condition of the battery in the electrical system to detect a fault in the battery; a physical component interrupting a current when the current through the physical component exceeds a predetermined level; wherein the battery can receive power from an external power source via a first electrical path, and the control circuit can receive power from the external power source via a second electrical path; When the electrical system is connected to the external power source, power is provided from the external power source to the control circuit via the second electrical path, and the control circuit determines a fault in the battery without charging the battery; the control circuitry enabling charging of the battery if there is no fault in the battery; A method comprising: sending a signal from said control circuit to said battery charger circuit for controlling operation of said battery charger circuit; the battery charger circuit controlling charging of the battery in response to the signal; The method of claim 7 further comprising:

9. providing power to the control circuit from the battery when the electrical system is not connected to the external power source; The method of claim 7 or 8, further comprising:

10. When executed on a computer or processor within an aerosol generating device including an electrical system, the computer or processor is caused to: a control circuit monitoring a condition of the battery in the electrical system to detect a fault in the battery; a physical component interrupting a current when the current through the physical component exceeds a predetermined level; wherein the battery can receive power from an external power source via a first electrical path, and the control circuit can receive power from the external power source via a second electrical path; When the electrical system is connected to the external power source, power is provided from the external power source to the control circuit via the second electrical path, and the control circuit determines a fault in the battery without charging the battery; the control circuitry enabling charging of the battery if there is no fault in the battery; A computer program comprising a set of instructions for executing the following:

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